Bioenergetics of Nestling Red-Backed Shrikes (Lanius collurio)

Bioenergetics of an experimental population and individual laboratory mice

“…In the ecological lite ra tu re to w hich I had access th ere is no inform ation on the energy balance of the developm ent period of o ther species of m am m als. Com parison of the results presented in th is study w ith analogical data contained for nesting birds of sim ilar body w eight shows, how ever, th a t effectiveness of production during the period of nest developm ent of mice is low er th an is the case w ith birds (Diehl & Myrcha, 1973;Myrcha et al, 1972). The value of K 2c calculated for the w hole nest period averages about 30%.…”

“…The value of K 2c calculated for the w hole nest period averages about 30%. Mice m ust assim ilate an average of 8.2 kcal of energy in order to produce 1 kcal of energy contained in the body tissu es, w hereas the nestlings of Lanius collurio L. assim ilate only 3.5 kcal for this purpose (Diehl & Myrcha, 1973). The values of the above indexes calculated for the first 17 days of life of these mice, during w hich the anim als w ere fed solely on th eir m o th er's m ilk, i.e.…”

Impact of Weather on Partial Loss of Nestlings in the Red-Backed ShrikeLanius collurioin Eastern Poland

“…This may be due to their food requirements, which are the highest during this period of nestling life. Laboratory studies showed that Red-backed Shrikes at the age of 6-10 days had food requirements at a level of 17-20 Kcal/24 h, while in the preceding period it was up to 11.5 Kcal/24 h (Diehl & Myrcha 1973). The difference between these values is not less than 33%.…”

“…Thus, under natural conditions, nestlings have to spend a remarkable amount of energy on maintaining a constant body temperature. Red-backed Shrikes reach the ability of effective thermoregulation in their 7-8 th day of life (Diehl & Myrcha 1973). The number of nestlings in broods can influence the amount of food provided to each nestling.…”

“…Such a division into time intervals was imposed by differences in the metabolism of nestlings in the period of their development. During studies on Red-backed Shrike nestlings in captivity, food requirements were the highest between the 6 th and 10 th day of nestling life (Diehl & Myrcha 1973). I reduced the number of visits to a Red-backed Shrike nest to the necessary minimum, as this species is especially vulnerable to disturbance and it often abandons broods (Tryjanowski & Kuźniak 1999).…”